/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.sky.logger.io;

import java.io.Serializable;
import java.io.Writer;

/**
 * {@link Writer} implementation that outputs to a {@link StringBuilder}.
 * <p>
 * <strong>NOTE:</strong> This implementation, as an alternative to
 * <code>java.io.StringWriter</code>, provides an <i>un-synchronized</i> (i.e.
 * for use in a single thread) implementation for better performance. For safe
 * usage with multiple {@link Thread}s then <code>java.io.StringWriter</code>
 * should be used.
 *
 * @version $Revision: 1003647 $ $Date: 2010-10-01 21:53:59 +0100 (Fri, 01 Oct
 *          2010) $
 * @since Commons IO 2.0
 */
public class StringBuilderWriter extends Writer implements Serializable {
	private static final long serialVersionUID = -8752672525456123647L;
	private final StringBuilder builder;

	/**
	 * Construct a new {@link StringBuilder} instance with default capacity.
	 */
	public StringBuilderWriter() {
		this.builder = new StringBuilder();
	}

	/**
	 * Construct a new {@link StringBuilder} instance with the specified capacity.
	 *
	 * @param capacity The initial capacity of the underlying {@link StringBuilder}
	 */
	public StringBuilderWriter(int capacity) {
		this.builder = new StringBuilder(capacity);
	}

	/**
	 * Construct a new instance with the specified {@link StringBuilder}.
	 *
	 * @param builder The String builder
	 */
	public StringBuilderWriter(StringBuilder builder) {
		this.builder = (builder != null ? builder : new StringBuilder());
	}

	/**
	 * Append a single character to this Writer.
	 *
	 * @param value The character to append
	 * @return This writer instance
	 */
	@Override
	public Writer append(char value) {
		builder.append(value);
		return this;
	}

	/**
	 * Append a character sequence to this Writer.
	 *
	 * @param value The character to append
	 * @return This writer instance
	 */
	@Override
	public Writer append(CharSequence value) {
		builder.append(value);
		return this;
	}

	/**
	 * Append a portion of a character sequence to the {@link StringBuilder}.
	 *
	 * @param value The character to append
	 * @param start The index of the first character
	 * @param end   The index of the last character + 1
	 * @return This writer instance
	 */
	@Override
	public Writer append(CharSequence value, int start, int end) {
		builder.append(value, start, end);
		return this;
	}

	/**
	 * Closing this writer has no effect.
	 */
	@Override
	public void close() {
	}

	/**
	 * Flushing this writer has no effect.
	 */
	@Override
	public void flush() {
	}

	/**
	 * Write a String to the {@link StringBuilder}.
	 * 
	 * @param value The value to write
	 */
	@Override
	public void write(String value) {
		if (value != null) {
			builder.append(value);
		}
	}

	/**
	 * Write a portion of a character array to the {@link StringBuilder}.
	 *
	 * @param value  The value to write
	 * @param offset The index of the first character
	 * @param length The number of characters to write
	 */
	@Override
	public void write(char[] value, int offset, int length) {
		if (value != null) {
			builder.append(value, offset, length);
		}
	}

	/**
	 * Return the underlying builder.
	 *
	 * @return The underlying builder
	 */
	public StringBuilder getBuilder() {
		return builder;
	}

	/**
	 * Returns {@link StringBuilder#toString()}.
	 *
	 * @return The contents of the String builder.
	 */
	@Override
	public String toString() {
		return builder.toString();
	}
}
